The present invention is concerned with a glass substrate for a magnetic disk, and were especially, it relates to a magnetic disk with a surface which has no chemical strengthening layer.
Moreover, the present invention relates to a magnetic disk whose surface roughness in an information recording portion thereof is sufficiently small, and a glass substrate for use in magnetic disk and magnetic disk that are suitable for a high density recording with high reliability. The present invention also relates to the process of manufacturing a glass substrate and a magnetic disk device.
Texturing of a glass substrate of a magnetic disk by using a laser has been attempted recently. While this method involves a technique used on metal substrates, such as Ni—P, this technique also maybe applied to glass. As described in Patent pre-publication 7-182655 and Patent prepublication 9-138942, laser texturing techniques using an ultraviolet light laser of 266 nm or a carbon dioxide laser that has a long wavelength of 10.6 μm have been used for ordinary glass having a transparency to light in the range from infrared to near ultraviolet.
In the above-described glass system, the substrate is reinforced by a chemical strengthening layer, and it is also known that texture formation maybe easily performed by compression of the substrate surface. (Ref. A. C. Tam et. al., IEEE(1997)).